Standard test article



Oct. 23, 1962 R. P. LAPPALA ETAL STANDARD TEST ARTICLE Filed July 20, 1959 FIGURE 2 FIGURE- 3 FIGURE I w A L E P A L P. 0 T 6 R 22 BP I NAGLER BY ie L ATTORNEY 3,059,463 STANDARD TEST ARTICLE Risto P. Lappala, Madison, and Robert T. Nagler, rairle du Sac, Wis., assignors to Bjorksten Research Laboratories, Inc., Fitchburg, Wis, a corporation of Illinois Filed July 20, 1959, Ser. No. 828,117 1 Claim. (Cl. 73-7) This invention relates to an apparatus for physically testing thin film and fabric materials for properties of abrasion resistance.

Testing procedures which have been developed for use in evaluating packaging materials for resistance to abrasive wear have been found to be generally inadequate to fulfill the requirements of a standard test method. A use ful standard test method must yield results which can be reproduced and which can be correlated with actual modes of failure that may be observed to occur in actual conditions of service.

In one conventional test procedure cartons are wrapped in a material which is to be tested and are tumbled on a vibrating table. Data which has been obtained from such testing shows that accentuated wear of the packaging material occurs at corner and edge portions of the test cartons in comparison to wear that is observed to occur in actual conditions of service.

In another conventional test procedure sand or grit material is cause to be impinged upon a packaging material by being carried in an air blast, by being hurled from a rotating wheel by centrifugal force, or by being brought into contact therewith by abrasive coated wheels, belts, or pads. The abrasive wear which occurs during such testing may be measured by the weight loss which is caused to occur in the tested material or by the time that is required to abrade the tested material to physical failure. The results of such testing cannot be satisfactorily correlated with wear which is observed to occur under conditions of actual service. The tests do not sufiiciently simulate the abrasive effect that is produced by relative motion between a packaged item and the material in which it is wrapped to be well suited for evaluation procedures.

This invention comprises an apparatus for abrading packaging materials in a manner which simulates actual conditions of use to which packaging materials may be subjected. The invention is particularly applicable for use with thin plastic film and other web materials which have high tensile strengths and which are susceptible to abrasive wear. In accordance with the invention an object of a particular configuration may be loosely placed within a film envelope and the envelope may then be sealed into a package form. The package may then be placed on a shaking table and the assembly be operably agitated until the packaging material is abraded by the object within the package to such extent that film failure occurs. The mode of failure and the time required for failure to occur may then be observed.

Film failure may be caused to occur by a roughened surface of an enclosed metal object having abraded the material to failure or may be caused to occur by an end portion of an enclosed metal object haw'ng worn a hole through the film material at a place on the film where the object point had been supported.

The results that may be obtained from the inventive procedure may be correlated with abrasive wear that may be observed to occur in service applications.

It is an object of this invention to provide a test apparatus for abrading film and fabric materials to physical failure.

It is a further object of this invention to provide a test apparatus that enables reproduceable results to be obtained ice 2 in testing abrasion resistance properties of packaging materials.

It is a still further object of this invention to provide a test apparatus that enables simple and expeditious testing of flexible film and fabric materials to be performed with a minimum of testing equipment.

Other objects will become apparent from the drawings and from the following detailed description in which it is intended to illustrate the applicability of the invention without thereby limiting its scope to less than that of all equivalents which will be apparent to one skilled in the art. In the drawings like reference numerals refer to like parts and:

FIGURE 1 is an elevation of an abrading device of this invention;

FIGURE 2 is a perspective view of a packaging material prepared for testing;

FIGURE 3 is a cross-sectional elevation of a testing apparatus.

In FIGURE 1 is shown object 20 which may be one of a plurality of similar objects which may be placed Within an enclosed envelope of material which is to be tested. In a preferred embodiment of this invention object 20 may be comprised of solid metal having a central rod like portion 21 with a surface having a high frictional coefficient and with blunted conical ends 22. Ends 22 are preferably smooth and configured in a conoidal shape with an apex of approximately 60 rounded sufficiently so as not to be enabled to lacerate film and fabric materials merely by coming into contact therewith subject to a small amount of kinetic energy. Central portion 21 is provided with a roughened surface which may operably abrade the material with which it is brought into contact in a manner which simulates relative movement between a packaged commodity and the packaging material within which a commodity might be enclosed.

Object 20, in a preferred embodiment of the invention, may be comprised of solid steel having a knurled surface machined on central portion 21 and having conical end portions 22 configured into conical sections with the apexes being configured with a radius of curvature of 0.0 2 inch. In another preferred embodiment of the invention object-2 0 may have a central portion 21 cut with standard machine threads with sharp crests having been re-, moved by a grinding or deburring and polishing operation. An object having a length of about two and one half inches and having a weight of approximately one hundred ten grams provides a highly satisfactory object for use in testing most synthetic film materials.

In FIGURE 2 is shown metal object 35, similar to the object 20 of FIGURE 1, sealed within closed package 38. Object 35 is shown configured as a portion of threaded shaft and is enclosed Within a square of material which is folded along edge 34 and sealed at edges 39. Edges 39 may be operably sealed by heat sealing, adhering together with adhesive, stapling, interlocking in an operable fashion or by any other suitable means. Package 38 is preferably only slightly larger than object 35 and must enclose object 35 in a manner which enables object 35 and package 38 to be displaced relative to each other through a distance measured in hundredths of an inch.

In FIGURE 3 are shown compartments of a box which are suitable for containing the apparatus shown in FIG- URE 2. The compartments that are shown may be of substantially right angular configuration except that side 45 may be disposed at an angle of approximately 30 to the bottom of the box. Side 45 may be extended across approximately three-quarters of the length of the compartment and across the entire width of the compartment. Package 38 of FIGURE 2 may be operably disposed within a compartment of box 40 of FIGURE 3 and the entire apparatus be placed on a vibrating table and be vibrated to cause object 35 of FIGURE 2 to repeatedly come into contact with the film material of package 38 of FIGURE 2. By imposing a vibratory motion on object 35 within package 38 relative motion between the two components is caused to occur 'as a result of a differential mass inertia between object 35 and the film component of package 38. The surfaces of the compartment of box 40 are preferably to be of a smooth non-abrading finish and in a preferred embodiment may be comprised of polished hardened sheet metal or of molded synthetic resinous material. Wooden surfaces have been found to be sufficiently susceptible to wear so as to cause abrasive wear to occur on the outer surfaces of package 38. Reproduceable test results can be obtained only by utilizing a box which does not itself cause abrasion of a test package contained therein. A box lined with aluminum, steel or other polished sheet metal material or with a rigid synthetic resinous material has been found to be satisfactory. The height and width of the compartment is preferably to be such that an object within the package being tested cannot wedge between two interior surfaces of the compartment so as to be restrained against movement within the compartment.

Objects such as object 20 of FIGURE 1 or object 35 of FIGURE 2 may be constructed of any solid material. The preferable shapes of such objects are those illus trated in FIGURES 1 and 2, but it is possible to provide a suitable object of rough cast material or of material with sand or grit material adhered thereto, or an object comprised of glass, porcelain, tile, or brick. It is also possible in non-preferred embodiments of this invention to employ the use of small machine components such as screws, nuts, bolts, or other variously configured small parts as abrading objects.

The results that may be obtained from the testing methods herein disclosed can be correlated with wear that may be observed to occur in actual packaging applications with greater accuracy than any method that has heretofore been disclosed. The disclosed testing method and apparatus are applicable to the testing of any flexible web material such as thermoplastic resinous compositions, cellulosic compositions, latex compositions, metal foils and impregnated or untreated fabrics. The inventive test method may also be used to test surface finishes such as paints, inks, varnishes, metal plating, anodizing, phosphatizing, chromating and other finishes.

The testing apparatus which is herein described is suitable for simultaneously testing a plurality of test compositions. An envelope which may contain abradin-g objects may be constructed from a plurality of Webs of various compositions by operably affixing the Webs together into one continuous sheet and forming the sheet into a closed container similar to package 38 of FIG- URE 2.

Package 38 of FIGURE 2 may contain fluid other than air such as other gases, vapors or liquids. The tests may be carried out in gas or vapor environments or in a liquid environment.

The object that may be used to 'abrade the material under test may be of the general configuration shown in FIGURE 1 or may be of other configurations such as those having shapes with two or three perpendicular principal axes, radially projecting lugged shafts or others.

A plurality of such objects may be used in the package of FIGURE 2.

The preferred configurations of the test packages and test compartments have been illustrated, but any volume of regular or irregular shape may be operably employed for a package or a compartment in accordance with the procedure that is herein disclosed.

While certain modifications and embodiments of the invention have been described, it is of course to be understood that there are a great number of variations which will suggest themselves to anyone familiar with the subject matter thereof and it is to be distinctly understood that this invention should not be limited except by such limitations as are clearly imposed in the appended claim.

N e claim:

An article of manufacture for use in testing the abrasion resistance of flexible materials comprising a closed envelope of flexible foldable material, a cylindrical solid object having conoidal shaped end extremities, the apexes of said end conoidal shapes being of arcuate configuration and the mid-portion of said object having a highly frictional surface, said solid object being enclosed in said envelope, said article providing a standard test package which may be used to determine the abrasion resistance of the material comprising said envelope.

References Cited in the file of this patent UNITED STATES PATENTS 970,373 Hemstreet Sept. 13, 1910 2,458,953 Mann Jan. 11, 1949 2,660,055 Thomrnen Nov. 24, 1953 2,825,225 Connell et al. Mar. 4, 1958 OTHER REFERENCES Page 640, Modern Packaging Encyclopedia for 1959, vol. 32, No. 3A, November 1958 issue. Received Scientific Library, U.S. Patent Office, Jan. 6, 1959. Call No. HF5770-P119.

Pages 41 and 42, Modern Packaging Encyclopedia for 1959, vol. 32, No. 3A, November 1958 issue. Received Scientific Library, U.S. Patent Office, January 6, 1959.

Page 646 and the chart opposite page 186, Modern Packaging Encyclopedia for 1958. Received Scientific Library, U.S. Patent Ofiice, Dec. 11, 1957. Call No. HF5770, p. 119.

Pages 109 and 110, The Packaging Engineering Handbook, by Walter Stern, published by Board Products Publishing Co, Chicago, 111., in 1949. Call No. I-IF5770 S75, 1949. 

